How to Build Plumbing Resilience In Your Community

The IAPMO Guide to Local Drinking Water and Wastewater Considerations

Our water systems are stressed.

Whether through the existence of aging or outdated plumbing and sewage systems or due to severe weather events exacerbated by the effects of climate change, millions of Americans live in communities with water under duress.

When it comes to water, resilient communities all have one thing in common: systems that provide their residents with safe and clean drinking water and effective wastewater removal, even in times of natural disasters or other crises.

Resilient communities start with plumbing. Plumbing systems are not one-size-fits-all, unlike other building and construction codes and standards. Plumbing is a local concern due to variances in regional climate, existing infrastructure, and local water quality, to name a few.

This is why plumbing codes and standards need to provide standardized customization. For example, the 2024 Uniform Plumbing Code (UPC) has 19 optional appendices to make it easy for jurisdictions to tailor the plumbing codes to local needs easily.

It takes deep expertise and specialized organizations like IAPMO to provide these holistic, customized solutions.

That is why IAPMO created this toolkit for community leaders, policymakers, and construction professionals to ensure that plumbing and mechanical system resilience is supported, encouraged, and tailored to the needs of their particular community.

What Are the Four Ways Plumbing Supports Community Resilience?

What Is Climate Resilience vs. Adaptation?

Barriers to Community Resiliency

Thunderstorms and High Wind Events

Floods and Coastal Hazard

Winter Storms and Freezing Weather

Food and Water Supply Contamination

Epidemic/Pandemic/Water-borne Disease

What Are the Four Ways Plumbing Supports Community Resilience?

Public Health + Safety

Science- and research-backed plumbing codes are the first line of defense in protecting the public from water-borne pathogens such as Legionella and healthcare-acquired infections (HAIs).

Disaster Mitigation + Recovery

Planning for and recovering from natural disasters is crucial to plumbing resiliency. Municipalities that address plumbing resiliency in their building codes – before disaster strikes — protect against water damage, ensure available drinking water, and promote safe wastewater disposal.

Sustainability + Efficiency

Water scarcity threatens our actual existence. Plumbing-resilient communities promote water conservation by setting guidelines for successfully implementing advanced water technologies such as greywater recycling and rainwater capture.

Affordability + Equity

Access to clean water and safe sanitation is a basic human right. Nevertheless, 2.2 million Americans live without a toilet or tap at home, a discrepancy that costs the U.S. economy more than $8.5 billion annually in health care, lost time, and premature death. Resilient communities drive solutions to close this water and sanitation access gap.

What Is Climate Resilience vs. Adaptation?

Climate resilience and climate adaptation are complementary approaches to climate change and should be implemented together to ensure the best possible outcomes for communities and ecosystems.

Climate resilience focuses on preparing communities and ecosystems to withstand the effects of climate change. By preparing for impacts such as extreme weather, rising temperatures, and changes in precipitation, communities, and ecosystems can be more resistant to their effects. This approach varies by region, including building infrastructure that is more resistant to natural disasters, such as floods, drought, and fires; strengthening the capacity of local communities to respond to climate change; and managing ecosystems to reduce their vulnerability to climate change.

Climate adaptation involves developing and implementing strategic measures that reduce the impacts of climate change on communities, ecosystems, and infrastructure. Examples of climate adaptation strategies include implementing policies and programs to reduce greenhouse gas emissions, improving water management systems, and conserving biodiversity.

Barriers to Community Resiliency

By combining climate resilience and adaptation, communities can better protect themselves from the effects of climate change while reducing their vulnerability to its long-term impacts.

But communities often face many barriers interfering with efforts to become resilient, including:

  • Aging and outdated plumbing infrastructure insufficient to address climate change and environmental inequities
  • Outdated codes, standards, and practices.
  • Insufficient availability of the workforce needed to make improvements.

Locally, natural disasters and other crises can negatively impact a community’s plumbing resiliency.


Drought is not everywhere in America, but it extensively affects the country. In the built environment, jurisdictions can effectively deploy resources that achieve 20% or more water savings.

Here are some drought-mitigation efforts and strategies for reducing water usage that have proven effective and are available in the Uniform Plumbing and Mechanical codes:

  • Alternate water sources and rainwater catchment systems can make up for water scarcity under drought conditions by using these sources for non-potable use, rather than relying on potable water for those uses.
  • Reduced potable water consumption guided by mandatory fixture flow rates and flush volumes.
  • Landscape performance criteria that reduce water needed for irrigation.
  • Pipe insulation that reduces heat loss through the pipes and maintains the desired temperature at tap, thus resulting in less water waste during drought.
  • Leak detection devices that mitigate potable water wastes from prolonged unnoticed leaks.
  • Accurate pipe sizing provides for faster hot water delivery times, reducing wasted shower water while waiting for water to warm up. Appendix M of the Uniform Plumbing Code with peak water demand calculations can be adopted as a standalone amendment to any plumbing code to facilitate these savings.

Access our Drought Mitigation Guide Toolkit.


Earthquakes can strike suddenly, at any time, and without warning. And the effects on plumbing systems can be devastating if strict standards aren’t maintained.

Piping systems are required, by code, to withstand extensive ground movement. This includes installing and maintaining bracing, hangers, and supports of sufficient strength to support the weight of the pipe and its contents and isolating them from incompatible materials. Minimum hanger supports are dictated by the pipe material used and how the pipes are angled (horizontal or vertical). They must be securely attached to the building construction at sufficiently close intervals to prevent the movement of piping.

Similarly, water heaters must be adequately restrained by anchors and/or straps to resist horizontal displacement where seismic conditions are likely to prevent fire by gas or electricity.

Medical gas and vacuum piping must also be seismically restrained against earthquakes where required.

Another factor is the composition of the ground soil where the piping is laid and where the building and structures they serve are built. It is critical to understand the specific makeup of the soil to predict shifts or movements that can cause damage to the structure, foundation, or the piping underneath.

Accordingly, pipes must be away from the load bearings of the building footers. Additionally, trenches are not allowed to be within a 45-degree angle from the foundation as it may reduce the bearing capacity of the soil for the foundation. Therefore, trenches are prohibited within the radial shear zone.

Earth movement is also considered for any leaks of piping buried underground. Underground water service piping needs to be separated by not less than one foot horizontally from building drain piping, building sewer piping, and non-potable water piping, including reclaimed water, greywater, and harvested rainwater. Potable water supply is required to be above any nearby sewer line. If the water piping leaks, gravity will pull it down towards the drain line, so the drain line needs to be below the potable water line to prevent contamination.


In the built environment, fire sprinkler systems mitigate fire and smoke damage. Multipurpose residential fire sprinkler systems that provide both domestic cold water distribution and fire sprinkler protection for one- and two-family dwellings with a combination piping system can also relieve the financial or economic stress on homeowner’s insurance providers by limiting the cost of damage.

Thunderstorms and High Wind Events

Roof drains, gutters and downspouts, foundation drains, and window well and window areaway drains are control and diversion techniques that help safeguard buildings and property from deluges. A vital mitigation tool in this regard is the proper installation of subsoil drains provided around the perimeter of buildings with basements, cellars, crawl spaces, or floors below grade.

Window areaways are particularly important during lightning events to protect CSST gas lines from energizing and causing fires.

Strong wind gusts passing over plumbing vent openings can cause pressure fluctuations in the drain, waste, and venting (DWV) system. Because winds can move harmful sewer gases from vents, it is important to consider wind conditions by requiring vent pipes above roofs to maintain minimum heights and distances to prevent sewer gases from polluting occupied areas.

Floods and Coastal Hazard

Damage from deluge events can be mitigated by controlling and/or capturing the excessive rainwater. Several prevention and mitigation efforts are available in areas prone to flooding – and increasingly, addressed through advanced codes.

Building codes should address the proper installation and maintenance of non-potable rainwater catchment systems and onsite stormwater treatment systems. These systems have proven advantageous in capturing floodwater onsite rather than redirecting it elsewhere – a key measure in preventing additional flooding elsewhere.

A significant requirement relates to the placement of the plumbing system; it must be above the elevation of the flooding hazards based on the specific geographic location of a jurisdiction. Plumbing systems should be designed and installed to prevent water from entering or accumulating within their components. Relatedly, all other plumbing systems need to be located above the elevation in accordance with the building code for utilities and attendant equipment or the elevation of the lowest floor, whichever is higher.

Backwater valves are another mitigating device to prevent flooding within the building. They should be required where fixtures and/or drain inlets are subject to backflow and overflow from blocked or restricted public sewers.

Winter Storms and Freezing Weather

In areas where winter storms with subfreezing temperatures and snow cover are common — and increasingly, in areas where they aren’t common, like the deep South — plumbing system ventilation is critical.

The height of vent terminals about the roof must anticipate clearance above a heavy snowstorm to maintain the proper function of the vent system. For jurisdictions having a minimum design temperature below 0°F (-17.8°C), the vent terminals need to be sized to prevent blockage due to frost closure.

The biggest issue impacting freezing events is when pipes burst. Freezing temperatures cause water to expand when changing from a liquid to a solid state, which can cause pipes to burst. Protection is required to keep pipes from freezing, and doing so also offers some methods of protecting potable water, such as using anti-freezing valves. Here are some realities to consider for piping in cold-weather environments:

  • Earth is an excellent insulator, so pipes should be buried below the local frost lines.
  • Since vents can frost over, additional requirements address frost build-up to prevent blockage of the vents. Some areas may require larger pipe sizes.
  • Piping should be installed so that the contents will not be heated due to close proximity to any heat source or from direct solar radiation. In areas with seasonal freezing outdoor temperatures, all drain piping and water piping installed in exterior walls, attics, and other areas exposed to outdoor temperatures need to be adequately protected from freezing. In heated spaces, the piping must be installed on the heated side of the building insulation.
  • Backflow devices and all water outlets also need protection from freezing.

Food and Water Supply Contamination

Preventing contamination of food and potable water is a critical public health issue. Maybe plumbing isn’t the first thing that comes to mind here, yet plumbing systems provide significant protection of food and water. For example, food being prepared or stored below piping hanging on the ceiling could be contaminated — leading to sickness or death — should any leaks occur.

Thus, proper methods for pipe installation and protection against leakage or condensation from such pipes must be practiced to ensure no contaminated water reaches the food or drink. Where building design requires that soil or drain pipes be located over such areas, the installation needs to be made with the least possible number of joints and installed to connect to the nearest adequately sized vertical stack.

In addition, openings through floors over such areas need to be sealed watertight to the floor construction. Floor and shower drains installed above such areas need to be equipped with integral seepage pans. Where pipes are installed in ceilings above such areas, the ceiling needs to be removable with access panels. The potable water supply must be designed, installed, and maintained to prevent contamination from non-potable liquids, solids, or gases by cross-connections.

UV Degradation

While the sun’s energy is needed for life, it can also decrease the lifespan of many materials when they are directly exposed to the sun’s harmful UV rays. When this occurs in plumbing systems, it can cause plastic piping to degrade and become brittle.

Therefore, plumbing vents of ABS and PVC piping shall be protected by water-based synthetic latex paint. PVC plastic water supply piping shall not be exposed to sunlight unless protected from UV degradation.

Epidemic/Pandemic/Water-borne Disease

Since 2000, the U.S. has seen a 450% increase in cases of Legionella, The Centers for Disease Control and Prevention (CDC) estimates as many as 18,000 hospitalizations occur annually because of Legionella, a water-borne illness with mortality rates ranging as high as 30%.

This is in part because of pipes that are sized incorrectly using an outdated formula that doesn’t account for water-saving fixtures. Water aging — which comes from water sitting in oversized pipes–creates an environment ripe for pathogen growth.

Water aging was also a concern after buildings were shuttered for months during the COVID-19 pandemic, due to stagnant water.

This increase in water-borne diseases has led the IAPMO plumbing committee to add an appendix to its Uniform Plumbing Code to address the Impact of Water Temperature on the Potential for Scalding and Legionella Growth. The Uniform Plumbing Code is the only plumbing code with provisions to help communities implement best practices in plumbing systems to minimize the threat of Legionella and other waterborne diseases.

Other considerations:

  • Dry traps are an avenue through which contamination spreads. Protecting the trap seal and floor drains from seal depletion is vitally important.
  • The COVID-19 epidemic also demonstrated the need for the resiliency of medical gas systems such as those used for ventilators.
  • Right-sized pipe reduces water aging in pipes by reducing stagnation time. The IAPMO Water Demand Calculator free app is a helpful tool.

Managing Water Age

Another helpful resource arose from an IAPMO and the American Water Works Association (AWWA) collaboration. The AWWA/IAPMO Manual-2022: Manual of Recommended Practices for the Safe Closure and Reopening of Building Water Systems is a manual of recommended practices to support providing safe and effective water efficiency and water quality provisions for the built environment.

Aging Population

By 2030, 21% of the US population will be 65+, up from 15% in 2016, according to the US Census.

Plumbing code provisions must address older occupants’ needs, especially given the risks inherent in bathrooms from falls and scalding. Occupants need to be safe getting in and out of bathing areas, while exposed waste and water supply piping for accessible sinks and lavatories need to be covered with protectors or insulators.

Housing Affordability

It can surprise people that accurately sizing plumbing pipes in new construction directly impacts housing affordability, but the numbers don’t lie.

Accurate pipe sizing can save up to $4,500 for new single-family home meter connections and can exceed $100,000 on a 45-unit multi-family building, especially where utility meter connection fees are high due to water scarcity.

Appendix M of the Uniform Plumbing Code with peak water demand calculations can be adopted as a standalone amendment to any plumbing code. In addition, IAPMO created a free Water Demand Calculator app to make it easier to save money on new construction.

Aging Infrastructure

Infrastructure failures due to aging plumbing systems lead to unsanitary conditions. In addition, older systems that still have lead in the plumbing pipes compromise drinking water safety. As the 2021 Infrastructure Investment and Jobs Act provides much-needed funding, plumbing resiliency needs to be a priority to address nearly all the issues identified above

Access Our Lead in Drinking Water Toolkit

The IAPMO Guide To Removing Lead From Drinking Water provides resources for communities, facilities managers, and consumers to understand the opportunities and requirements necessary to finally fix this public health issue and ensure safe, clean drinking water for all.

FEMA and Building Codes

The Federal Emergency Management Administration (FEMA) does not mandate the use of any particular building code or standard. In 2019, FEMA issued an interim guidance document, the “Disaster Risk Reduction Minimum Codes and Standards,” which explains that, after a disaster, buildings being built back using FEMA funds must be built using the latest nationally-recognized voluntary consensus-based building codes and standards.

In a memo published in September 2022, FEMA stated that “Applicants are not limited to using the codes, specifications, and standards listed in the appendix to be eligible for Public Assistance funding. Applicants who use different state or locally adopted codes, specifications, or standards with resilience criteria that are comparable to, or more stringent than, those listed in the appendix are eligible for funding and will be reimbursed for those costs.”